[Paleopsych] SW: Social Hierarchy and Primate Health

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Sociobiology: Social Hierarchy and Primate Health

    The following points are made by Robert M. Sapolsky (Science 2005
    1) One of the greatest challenges in public health is to understand
    the "socioeconomic gradient." This refers to the fact that in numerous
    Westernized societies, stepwise descent in socioeconomic status (SES)
    predicts increased risks of cardiovascular, respiratory, rheumatoid,
    and psychiatric diseases; low birth weight; infant mortality; and
    mortality from all causes [1-4]. This relation is predominately due to
    the influence of SES on health, rather than the converse, and the
    disease incidences can be several times greater at the lower extreme
    of the SES spectrum.
    2) One set of questions raised by the gradient concern its external
    causes. Despite human aversion to inequity in some settings [5], many
    Westernized societies tolerate marked SES gradients in health care
    access. Is this the predominant cause of the health gradient, or is it
    more a function of differences in lifestyle risk factors or of the
    psychosocial milieu in which poverty occurs?
    3) Another set of questions concern the physiological mediators of the
    SES-health relationship -- how, in a frequently used phrase in the
    field, does poverty get under the skin? These physiological questions
    are difficult to study in humans, and an extensive literature has
    focused instead on nonhuman animals. Despite the demonstration that
    some nonhuman species can also be averse to inequity, groups of social
    animals often form dominance hierarchies, producing marked
    inequalities in access to resources. In such cases, an animal's
    dominance rank can dramatically influence the quality of its life.
    Does rank also influence the health of an animal?
    4) The study of rank-health relations in animals has often been framed
    in the context of stress and the idea that animals of different ranks
    experience different patterns of stress. A physical stressor is an
    external challenge to homeostasis. A psychosocial stressor is the
    anticipation, justified or not, that a challenge to homeostasis looms.
    Psychosocial stressors typically engender feelings of lack of control
    and predictability and a sense of lacking outlets for the frustration
    caused by the stressor. Both types of stressor activate an array of
    endocrine and neural adaptations. When mobilized in response to an
    acute physical challenge to homeostasis (such as fleeing a predator),
    the stress response is adaptive, mobilizing energy to exercising
    muscle, increasing cardiovascular tone to facilitate the delivery of
    such energy, and inhibiting unessential anabolism, such as growth,
    repair, digestion, and reproduction. Chronic activation of the stress
    response by chronic psychosocial stressors (such as constant close
    proximity to an anxiety-provoking member of one's own species) can
    increase the risk of numerous diseases or exacerbate such preexisting
    diseases as hypertension, atherosclerosis, insulin-resistant diabetes,
    immune suppression, reproductive impairments, and affective disorders.
    5) In summary: Dominance hierarchies occur in numerous social species,
    and rank within them can greatly influence the quality of life of an
    animal. The author considers how rank can also influence physiology
    and health. The author first considers whether it is high- or
    low-ranking animals that are most stressed in a dominance hierarchy;
    this turns out to vary as a function of the social organization in
    different species and populations. The author then reviews how the
    stressful characteristics of social rank have adverse adrenocortical,
    cardiovascular, reproductive, immunological, and neurobiological
    consequences. Finally, the author considers how these findings apply
    to the human realm of health, disease, and socioeconomic status.
    References (abridged):
    1. N. Adler et al., Health Psychol. 19, 586 (2000)
    2. I. Kawachi, B. Kennedy, The Health of Nations: Why Inequality Is
    Harmful to Your Health (New Press, New York, 2002)
    3. J. Siegrist, M. Marmot, Soc. Sci. Med. 58, 1463 (2004)
    4. R. Wilkinson, Mind the Gap: Hierarchies, Health, and Human
    Evolution (Weidenfeld and Nicolson, London, 2000)
    5. E. Fehr, B. Rockenbach, Curr. Opin. Neurobiol. 14, 784 (2004)
    Science http://www.sciencemag.org
    Related Material:
    The following points are made by S.L. Isaacs and S.A. Schroeder (New
    Engl. J. Med. 2004 351:1137):
    1) The health of the American public has never been better. Infectious
    diseases that caused terror in families less than 100 years ago are
    now largely under control. With the important exception of AIDS and
    occasional outbreaks of new diseases such as the severe acute
    respiratory syndrome (SARS) or of old ones such as tuberculosis,
    infectious diseases no longer constitute much of a public health
    threat. Mortality rates from heart disease and stroke -- two of the
    nation's three major killers --have plummeted.(1)
    2) But any celebration of these victories must be tempered by the
    realization that these gains are not shared fairly by all members of
    our society. People in upper classes -- those who have a good
    education, hold high-paying jobs, and live in comfortable
    neighborhoods -- live longer and healthier lives than do people in
    lower classes, many of whom are black or members of ethnic minorities.
    And the gap is widening.
    3) A great deal of attention is being given to racial and ethnic
    disparities in health care.(2-5) At the same time, the wide
    differences in health between the haves and the have-nots are largely
    ignored. Race and class are both independently associated with health
    status, although it is often difficult to disentangle the individual
    effects of the two factors.
    4) The authors contend that increased attention should be given to the
    reality of class and its effect on the nation's health. Clearly, to
    bring about a fair and just society, every effort should be made to
    eliminate prejudice, racism, and discrimination. In terms of health,
    however, differences in rates of premature death, illness, and
    disability are closely tied to socioeconomic status. Concentrating
    mainly on race as a way of eliminating these problems downplays the
    importance of socioeconomic status on health.
    5) The focus on reducing racial inequality is understandable since
    this disparity, the result of a long history of racism and
    discrimination, is patently unfair. Because of the nation's history
    and heritage, Americans are acutely conscious of race. In contrast,
    class disparities draw little attention, perhaps because they are seen
    as an inevitable consequence of market forces or the fact that life is
    unfair. As a nation, we are uncomfortable with the concept of class.
    Americans like to believe that they live in a society with such
    potential for upward mobility that every citizen's socioeconomic
    status is fluid. The concept of class smacks of Marxism and economic
    warfare. Moreover, class is difficult to define. There are many ways
    of measuring it, the most widely accepted being in terms of income,
    wealth, education, and employment.
    6) Although there are far fewer data on class than on race, what data
    exist show a consistent inverse and stepwise relationship between
    class and premature death. On the whole, people in lower classes die
    earlier than do people at higher socioeconomic levels, a pattern that
    holds true in a progressive fashion from the poorest to the richest.
    At the extremes, people who were earning $15,000 or less per year from
    1972 to 1989 (in 1993 dollars) were three times as likely to die
    prematurely as were people earning more than $70,000 per year. The
    same pattern exists whether one looks at education or occupation. With
    few exceptions, health status is also associated with class.
    References (abridged):
    1. Institute of Medicine. The future of the public's health in the
    21st century. Washington, D.C.: National Academies Press, 2003:20.
    2. Smedley BD, Stith AY, Nelson AR, eds. Unequal treatment:
    confronting racial and ethnic disparities in health care. Washington,
    D.C.: National Academy Press, 2003
    3. Steinbrook R. Disparities in health care -- from politics to
    policy. N Engl J Med 2004;350:1486-1488
    4. Burchard EG, Ziv E, Coyle N, et al. The importance of race and
    ethnic background in biomedical research and clinical practice. N Engl
    J Med 2003;348:1170-1175
    5. Winslow R. Aetna is collecting racial data to monitor medical
    disparities. Wall Street Journal. March 5, 2003:A1
    New Engl. J. Med. http://www.nejm.org

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